Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net (loss) income	$ (1,561)	$ 10,018	$ (134,779)	$ 22,328	$ 27,396	$ 23,917	$ 21,390	$ 31,643	$ (103,994)	$ 104,346	$ 80,354
Less: Net income allocated to unvested participating restricted stock									(420)	(3,532)	(2,711)
Net (loss) income available to common stockholders									(104,414)	100,814	77,643
Effect of unvested participating restricted stock									0	33	16
(Loss) income available to common shareholders - diluted									$ (104,414)	$ 100,847	$ 77,659
Weighted average outstanding shares of common stock - basic (in shares)									16,230,000	16,934,000	17,533,000
Stock options (in shares)									0	311,000	256,000
Weighted average outstanding shares of common stock - diluted (in shares)									16,230,000	17,245,000	17,789,000
Basic (in dollars per share)	$ (0.10)	$ 0.60	$ (8.33)	$ 1.33	$ 1.61	$ 1.38	$ 1.20	$ 1.76	$ (6.43)	$ 5.95	$ 4.43
Diluted (in dollars per share)	$ (0.10)	$ 0.60	$ (8.33)	$ 1.31	$ 1.59	$ 1.36	$ 1.18	$ 1.73	$ (6.43)	$ 5.85	$ 4.37
Antidilutive securities excluded from computation of earnings per share (in shares)									100,056